Emergency Contraception

Topic Overview

What is emergency contraception?

Emergency contraception is a way to prevent pregnancy if:

  • You had sex without using birth control.
  • Your birth control method failed. Maybe you forgot to take your pill or get your shot, the condom broke or came off, or your diaphragm slipped.
  • You were raped. Even if you were using birth control, emergency contraception can help decrease your chance of getting pregnant.

If you had sex without birth control, there is a chance that you could get pregnant. This is true even if you have not started having periods yet or you are getting close to menopause. You could also get pregnant if you used a birth control method that is not very reliable or if you didn't use it the right way.

Using emergency contraception right away can prevent an unwanted pregnancy and keep you from worrying while you wait for your next period to start.

What are the types of emergency contraception?

There are two types of emergency contraception: pills and the copper T intrauterine device (IUD). Most women choose pills because they work well, don't cost a lot, and are usually easy to get. The IUD works very well, but it costs a lot and has to be inserted by a doctor.

Pills : Pills used for emergency contraception are sometimes called “morning-after pills.” They can be used at any time up to 5 days after unprotected sex, but the sooner, the better. They contain hormones—either progestin only or a combination of estrogen and progestin.

  • Levonorgestrel, such as Plan B or Next Choice, is a progestin-only pill that is packaged specially for use as emergency contraception. The cost of a single-use package is about $25 to $40.
  • Some birth control pills are also used. If you already take birth control pills, you may be able to use the pills you have as emergency contraception. Talk to your doctor or check the Web sites listed below for the correct doses.

IUD : The copper T IUD is a small, T-shaped plastic device that is inserted into your uterus. The IUD is wrapped in copper, which helps kill sperm. It can be placed up to 5 to 7 days after unprotected sex to prevent pregnancy. (Note: The Mirena IUD is not used for emergency contraception.)

  • Copper T IUDs work very well but are usually expensive—around $400 to $500.
  • On the plus side, after a copper T IUD is in place, it keeps working for up to 10 years.

An IUD is not a good idea if you have a pelvic infection or sexually transmitted disease (STD). It could spread the infection and cause pelvic inflammatory disease, a serious health problem that can affect your ability to have children.

How does it work?

Emergency contraception pills work by preventing ovulation, fertilization, or implantation.

Emergency contraception hormones may prevent fertilization by stopping the ovary from releasing an egg (ovum). They also make the fallopian tubes less likely to move an egg toward the uterus. Emergency contraception is also thought to thin the lining of the uterus, or endometrium. The thickened endometrium is where a fertilized egg would normally implant and grow.

Where can you get emergency contraception?

Emergency Contraception. You can buy emergency contraception, such as Plan B or Next Choice, in most drugstores.

  • If you are 17 or older, you can get emergency contraception from a pharmacist, without a prescription. Bring proof of your age.
  • If you are younger than 17, you can get emergency contraception with a prescription from a doctor.

Birth control pills. If you already have birth control pills on hand, you may be able to use them for emergency birth control. To find out which brands of pills work and how to take them, go to:

  • The Planned Parenthood Web site at http://plannedparenthood.org.
  • The Emergency Contraception Web site at http://ec.princeton.edu.

Some pharmacists will not sell emergency contraception or fill prescriptions for birth control pills. If this happens to you, ask for the location of a pharmacist who will, or go to:

  • The Emergency Contraception Web site at http://ec.princeton.edu, or call 1-888-NOT-2-LATE.
  • The Planned Parenthood clinic nearest you, or call 1-800-230-PLAN (1-800-230-7526).

IUD. You can get an IUD from many doctors, from college and public health clinics, or in most hospital emergency rooms. An IUD has to be inserted by a doctor or other health professional.

How do you use it?

For the emergency contraception option that contains 2 pills, you can take both pills at the same time. Or you can take 1 pill right away and the second pill 12 hours later.

There is also a one-pill emergency contraception option that lets you take the dose you need in just 1 pill.

For most regular birth control pills, you take one dose of 2 to 5 pills as soon as you can. Then you take a second dose 12 hours later. The dose depends on the type of pill.

You can take emergency contraception up to 5 days after unprotected sex. But it works best if you take it right away or within 48 hours.

If you use birth control pills for emergency contraception, keep the following in mind:

  • Birth control pills can cause nausea. Take an antinausea medicine such as Dramamine with the first dose and again 1 hour before the second dose.
  • If you vomit within 2 hours of taking the pills, call your doctor for advice. You may need to repeat the dose.
  • Be sure you take the active hormone pills. In a 28-day pack, the first 21 pills contain hormones. The last 7 pills (the ones you take during your period) do not contain any hormones. If you use 21-day packs, all of the pills contain hormones.

A doctor or other health professional has to insert an IUD.

How well does it work?

Emergency contraception works very well. The sooner you use it, the more likely it is to prevent pregnancy. Overall:1

  • Plan B is very effective. Only about 1 woman out of 100 who uses it will get pregnant, if taken within 48 hours.
  • Birth control pills are around 97% to 98% effective. Only about 2 or 3 women out of 100 who use them as emergency contraception will get pregnant.
  • The copper T IUD is more than 99% effective. Only about 1 woman out of 1,000 who use it will get pregnant.

If you haven't started your period within 3 weeks after using emergency contraception, get a pregnancy test.

Does it cause side effects?

Emergency contraception may cause some side effects.

  • Levonorgestrel may cause spotting or mild symptoms like those of birth control pills. It usually doesn't cause nausea.
  • Birth control pills can cause nausea or vomiting. In some women, they can also cause sore breasts, fatigue, headache, belly pain, or dizziness.
  • An IUD may cause cramping and bleeding during the first few days after insertion.

Call your doctor if you have a headache, dizziness, or belly pain that is severe or that lasts longer than 1 week.

If you are already pregnant, pills won't harm the fetus. An IUD could cause problems with the pregnancy.

What else should you think about?

  • Emergency contraception pills won't protect you for the rest of your cycle. Use your regular method of birth control, or use condoms.
  • Unless you get an IUD, emergency contraception does not take the place of regular birth control. Find a good method of birth control you can use every time you have sex.
  • Emergency contraception does not prevent sexually transmitted diseases. If you are worried you might have been exposed to a disease, talk to your doctor.
  • Accidents can happen. It is a good idea to keep a set of the pills on hand in case you ever need it.

Other Places To Get Help


Emergency Contraception Website
Phone: 1-888-NOT-2-LATE (1-888-668-2528)
Web Address: ec.princeton.edu

This Web site provides information about emergency contraception. This includes the correct use, effectiveness, and expected side effects of emergency contraception, along with how regular contraceptive pills can be used for emergency contraception. The Web site is operated by the Office of Population Research at Princeton University and by the Association of Reproductive Health Professionals.

A searchable database of emergency contraceptive providers in the United States is also available.

Planned Parenthood's Emergency Contraceptive Page
Phone: 1-800-230-PLAN or 1-800-230-7526
Web Address: www.plannedparenthood.org/ec

This site offers resources for emergency contraception, including birth control pills available for this use and their side effects, the use of an intrauterine device (IUD), and a fact sheet.

Information on this site is also provided in Spanish.



  1. Zieman M, et al. (2007). Emergency contraception. In Managing Contraception for Your Pocket, 2007–2009 ed., pp. 73–81. Tiger, GA: Bridging the Gap Foundation.

Other Works Consulted

  • American Academy of Pediatrics (2005). Policy statement: Emergency contraception. Pediatrics, 116(4): 1026–1035.
  • Raymond E (2005). Emergency contraception. ACOG Practice Bulletin No. 69. Obstetrics and Gynecology, 106(6): 1443–1452.


Author Bets Davis, MFA
Editor Maria G. Essig, MS, ELS
Associate Editor Denele Ivins
Associate Editor Pat Truman, MATC
Associate Editor Michele Cronen
Primary Medical Reviewer Joy Melnikow, MD, MPH - Family Medicine
Specialist Medical Reviewer Kirtly Jones, MD - Obstetrics and Gynecology
Last Updated May 22, 2008

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